Potential & Enhancement System Guide

For the Self-skills, this is my theory on it

Any level of the item can get the respective skill, meaning you can have a wg that gives SE. But you can only use the skill SE if you are 120.

This makes some sense taking a look at the levels. Door, HB, haste are all 70+ while SE is 120, due to SE being a 4th job skill. This doesn't exactly explain why HB and Haste are level 70 and not 30, but I think it's relevant to consider.

a post on sleepywood shows that the item was unique and level 90, so i would assume the level requirement is player level and player patience and luck.